U.S. patent number 10,761,884 [Application Number 16/004,432] was granted by the patent office on 2020-09-01 for control device for operating multiple types of programs in different execution formats.
This patent grant is currently assigned to OMRON Corporation. The grantee listed for this patent is OMRON Corporation. Invention is credited to Tetsushi Jakunen, Masahiko Nakano, Junji Shimamura, Tomonori Shimamura, Eiji Yamamoto.
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United States Patent |
10,761,884 |
Shimamura , et al. |
September 1, 2020 |
Control device for operating multiple types of programs in
different execution formats
Abstract
A control device includes at least a first task that has a first
priority including processing execution performed by a program
execution part and a command calculation part, a second task that
has a second priority, lower than the first priority, including
processing execution performed by a parsing part, and a third task
that has a third priority including execution of a processing
content different from the first task and the second task are set
in a scheduler. The control device further includes a priority
changing part monitoring a processing state of the parsing part,
and when the processing state of the parsing part meets a
predetermined condition, changing the second priority set to the
second task corresponding to the condition.
Inventors: |
Shimamura; Junji (Takatsuki,
JP), Jakunen; Tetsushi (Kusatsu, JP),
Shimamura; Tomonori (Otsu, JP), Yamamoto; Eiji
(Kyoto, JP), Nakano; Masahiko (Ritto, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
OMRON Corporation |
Kyoto |
N/A |
JP |
|
|
Assignee: |
OMRON Corporation (Kyoto,
JP)
|
Family
ID: |
62684597 |
Appl.
No.: |
16/004,432 |
Filed: |
June 11, 2018 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20190095247 A1 |
Mar 28, 2019 |
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Foreign Application Priority Data
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Sep 26, 2017 [JP] |
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2017-185146 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G05B
19/4145 (20130101); G05B 19/4148 (20130101); G05B
19/408 (20130101); G05B 19/41865 (20130101); G06F
9/4881 (20130101); G06F 9/505 (20130101); G05B
2219/15079 (20130101); G05B 2219/1215 (20130101); G05B
2219/34287 (20130101); G05B 2219/23275 (20130101) |
Current International
Class: |
G05B
19/414 (20060101); G05B 19/408 (20060101); G06F
9/50 (20060101); G05B 19/418 (20060101); G06F
9/48 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2001027904 |
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Jan 2001 |
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2001027904 |
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Jan 2001 |
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JP |
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2001034320 |
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Feb 2001 |
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JP |
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2004152322 |
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May 2004 |
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JP |
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2010033150 |
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Feb 2010 |
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JP |
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2015176191 |
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Oct 2015 |
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JP |
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2016012221 |
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Jan 2016 |
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JP |
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2016092544 |
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May 2016 |
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JP |
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2016092544 |
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May 2016 |
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JP |
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WO-2019061466 |
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Apr 2019 |
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WO |
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Other References
"Search Report of Europe Counterpart Application", dated Apr. 11,
2019, p. 1-p. 7. cited by applicant .
"Office Action of Japan Counterpart Application", dated Mar. 10,
2020, with English translation thereof, p. 1-p. 9. cited by
applicant.
|
Primary Examiner: Ghaffari; Abu Zar
Attorney, Agent or Firm: JCIPRNET
Claims
What is claimed is:
1. A control device comprising: a storage device storing a first
program that is entirely scanned for every execution and a second
program that is executed sequentially; and one or more processors,
configured to: execute the first program at every first cycle to
output a first control command; parse at least a part of the second
program at every second cycle, which is longer than the first
cycle, to sequentially generate an internal command; output a
second control command at every first cycle according to the
internal command; execute a scheduler to allocate a processor
resource to one or more tasks based on a preset priority, wherein
at least a first task that has a first priority comprising
processing execution performed by the program execution and the
command calculation by the processor, a second task that has a
second priority, lower than the first priority, comprising
processing execution performed by the parsing by the processor, and
a third task that has a third priority comprising execution of a
processing content different from the first task and the second
task are set in the scheduler; and monitor a processing state of
the parsing, and when the processing state of the parsing meets a
predetermined condition, change the second priority based on a
ratio between a length of the second cycle and a time required for
the processing execution of the second task according to the
condition, wherein the processor determines the processing state of
the parsing based on information that indicates a load related to a
generation process of the internal command, and wherein the
information that indicates the load comprises information of
whether a time required for parsing of the second program performed
by the processor exceeds the length of the second cycle.
2. The control device according to claim 1, wherein the processor
is configured to parse the second program to calculate a plurality
of passing points on a trajectory of a robot at a plurality of
times and generate the internal command based on the calculated
passing point, wherein the information that indicates the load
comprises a number of the passing points that the processor
calculates in advance for generating the internal command.
3. The control device according to claim 2, wherein the information
that indicates the load comprises a number of internal commands,
which have not yet been processed by the processor, among the
internal commands generated by the processor.
4. The control device according to claim 1, wherein the information
that indicates the load comprises a number of internal commands,
which have not yet been processed by the processor, among the
internal commands generated by the processor.
5. The control device according to claim 1, wherein the information
that indicates the load comprises a special command described in
the second program, wherein when the special command described in
the second program is executed, the processor changes the second
priority of the second task or the priority of the task related to
the second task.
6. The control device according to claim 1, wherein the processor
raises the second priority that has been set to the second task,
and then restores the second priority when another predetermined
condition is met.
7. The control device according to claim 1, wherein the processor
is configured to execute parsing on a plurality of the second
programs respectively to sequentially generate respective internal
commands, wherein the processor changes priorities of a plurality
of the second tasks associated with the parsing of the second
programs.
Description
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the priority benefit of Japan application
serial no. 2017-185146, filed on Sep. 26, 2017. The entirety of the
above-mentioned patent application is hereby incorporated by
reference herein and made a part of this specification.
BACKGROUND
Technical Field
The invention relates to a control device for controlling a control
object.
Description of Related Art
Various FA (Factory Automation) technologies have been used widely
at production sites. Such FA systems may include not only control
devices such as PLC (programmable logic controller) but also
various actuators that are capable of performing advanced
operations such as CNC (computer numerical control) and robot. Such
FA systems tend to be larger in scale.
For example, Japanese Laid-open Patent Application No. 2001-027904
discloses a numerical control system that can increase the number
of axes under control by connecting multiple CNC devices, and
synchronize the CNC devices. In this numerical control system, a
master unit and one or more slave units are connected via a cable.
The master unit and the slave units each have a PMC processor and a
CNC processor for executing a ladder program.
In addition, Japanese Laid-open Patent Application No. 2016-092544
discloses a control system that controls a first control object by
a master control device and controls a second control object,
different from the first control object, by a slave control device
connected to the master control device via a network. This control
system includes the master control device and the slave control
device. Apart from the controller that has an arithmetic processing
part, the master control device and the slave control device each
include a robot controller having another arithmetic processing
part.
As the ICT (information and communication technology) advances in
recent years, the processing capability of control devices is also
improving dramatically. There is also a need to realize the FA
system, which has been realized with use of multiple dedicated
devices in the related art, with fewer control devices.
In the configurations disclosed in the aforementioned patent
documents, a plurality of processors or arithmetic processing parts
are dispersively arranged, and in order to achieve synchronous
processing between the processors or arithmetic processing parts,
the configurations may become redundant.
Furthermore, for realizing multiple types of programs (e.g., ladder
program, CNC program, robot program, etc.) in different execution
formats with one single control device, it is necessary to
efficiently use the limited processing resources. The invention
thus provides a control device.
SUMMARY
According to an embodiment of the disclosure, a control device
having one or more processors is provided. The control device
includes: a storage part storing a first program that is scanned as
a whole for every execution and a second program that is executed
sequentially; a program execution part executing the first program
at every first cycle to output a first control command; a parsing
part parsing at least a part of the second program at every second
cycle, which is longer than the first cycle, to sequentially
generate an internal command; a command calculation part outputting
a second control command at every first cycle according to the
internal command generated by the parsing part; and a scheduler
allocating a processor resource to one or more tasks based on a
preset priority. At least a first task that has a first priority
including processing execution performed by the program execution
part and the command calculation part, a second task that has a
second priority, lower than the first priority, including
processing execution performed by the parsing part, and a third
task that has a third priority including execution of a processing
content different from the first task and the second task are set
in the scheduler. The control device further includes a priority
changing part monitoring a processing state of the parsing part,
and when the processing state of the parsing part meets a
predetermined condition, changing the second priority that has been
set to the second task according to the condition.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A and FIG. 1B are time charts for illustrating the outline of
processing in the control device according to the embodiment.
FIG. 2 is a schematic diagram showing an example of the overall
configuration of the control system according to the
embodiment.
FIG. 3 is a block diagram showing an example of the hardware
configuration of the control device according to the
embodiment.
FIG. 4 is a block diagram showing an example of the functional
configuration of the control device according to the
embodiment.
FIG. 5A and FIG. 5B are schematic diagrams for illustrating the
generation process of an internal command in the control device
according to the embodiment.
FIG. 6 is a time chart showing an example of task execution timing
in the control device according to the embodiment.
FIG. 7 is a time chart showing an example of a task execution cycle
excess of the low priority task in the control device according to
the embodiment.
FIG. 8 is a diagram showing an example of the variable list that
shows the time required for processing execution in the control
device according to the embodiment.
FIG. 9A and FIG. 9B are schematic diagrams for illustrating an
example of the generation process of an internal command in the
control device according to the embodiment.
FIG. 10 is a schematic diagram showing an example of processing of
a passing point for generating an internal command in the control
device according to the embodiment.
FIG. 11 is a schematic diagram showing an example of processing for
calculating a control command from an internal command in the
control device according to the embodiment.
FIG. 12A and FIG. 12B are schematic diagrams showing an example of
the application program processed in the control device according
to the embodiment.
FIG. 13 is a flowchart showing a processing procedure of priority
change in the control device according to the embodiment.
FIG. 14 is a time chart showing an example of execution timing when
a plurality of application programs are executed in parallel in the
control device according to the embodiment.
FIG. 15 is a schematic diagram for illustrating an overlap
operation provided by the control device according to the
embodiment.
FIG. 16 is a schematic diagram showing an example of the program
for realizing the overlap operation in the control device according
to the embodiment.
FIG. 17 is a schematic diagram showing an example of the overlap
operation when time is set as the overlap condition.
FIG. 18 is a schematic diagram showing an example of the overlap
operation when position is set as the overlap condition.
FIG. 19 is a schematic diagram showing the functional configuration
for realizing the overlap operation in the control device according
to the embodiment.
DESCRIPTION OF THE EMBODIMENTS
According to the disclosure, in the case where multiple tasks share
a common processor resource, it is possible to prevent the
situation that the internal command serving as the source for
generating the control command is not generated in time, so as to
guarantee output of the control commands according to the first
program and the second program at every first cycle.
According to an embodiment of the disclosure, the priority changing
part may determine the processing state of the parsing part based
on information that indicates a load related to a generation
process of the internal command performed by the parsing part.
According to the disclosure, since it is possible to evaluate the
load state of the parsing part subject to the priority change
substantially, the stability of the priority changing process can
be improved.
According to an embodiment of the disclosure, the information that
indicates the load may include a time required for parsing of the
second program performed by the parsing part.
According to the disclosure, since it is possible to objectively or
quantitatively evaluate the load state of parsing of the second
program performed by the parsing part, the priority can be raised
before the load of the parsing part becomes excessive, so as to
prevent occurrence of the situation that the internal command is
not generated in time.
According to an embodiment of the disclosure, the information that
indicates the load may include information of whether the time
required for parsing of the second program performed by the parsing
part exceeds a length of the second cycle.
According to the disclosure, since the priority is changed based on
the fact that the parsing of the second program performed by the
parsing part exceeds the original cycle, the situation of
unnecessary change of the priority can be prevented.
According to an embodiment of the disclosure, the parsing part may
be configured to parse the second program to calculate a passing
point on a trajectory and generate the internal command based on
the calculated passing point. The information that indicates the
load may include a number of passing points that the parsing part
calculates in advance for generating the internal command.
According to the disclosure, it is possible to evaluate the
processing load of the parsing of the second program performed by
the parsing part, and prevent the situation that the internal
command is not generated in time.
According to an embodiment of the disclosure, the information that
indicates the load may include a number of internal commands, which
have not yet been processed by the command calculation part, among
the internal commands generated by the parsing part.
According to the disclosure, it is possible to prevent the
situation that the generation of the internal command does not
catch up and causes the output of the control command performed by
the parsing part to be suspended.
According to an embodiment of the disclosure, the information that
indicates the load may include a special command described in the
second program.
According to the disclosure, since it is possible to directly
instruct processing of a specific command among the commands
described in the second program with a higher priority, the parsing
of the second program and the generation of the internal command
can be realized more reliably.
According to an embodiment of the disclosure, the priority changing
part may raise the second priority that has been set to the second
task, and then restore the second priority when another
predetermined condition is met.
According to the disclosure, more processor resource is allocated
to the parsing part for parsing the second program only when
required. When not required, the parsing part does not occupy the
processor resource and the processor resource can be allocated to
other tasks.
According to an embodiment of the disclosure, the parsing part may
be configured to execute parsing on a plurality of the second
programs respectively to sequentially generate respective internal
commands. The priority changing part may change priorities of a
plurality of the second tasks associated with the parsing of the
second programs.
According to the disclosure, in the control device, when the
control according to multiple second programs is executed in
parallel, arbitration between the priorities of the second programs
can be performed.
According to the disclosure, it is possible to efficiently operate
multiple types of programs in different execution formats on one
single control device.
Embodiments of the invention are described in detail hereinafter
with reference to the figures. In the figures, identical or
corresponding parts are denoted by the same reference numerals and
descriptions thereof will not be repeated.
A. Example of Application
First, an example of the situation, to which the invention is
applied, is described with reference to FIG. 1A and FIG. 1B. FIG.
1A and FIG. 1B are time charts for illustrating the outline of
processing in a control device 100 according to the embodiment.
Referring to FIG. 1A and FIG. 1B, in the control device 100
according to the embodiment, at least a first program that is
scanned as a whole in each execution and a second program that is
executed sequentially are both executed.
In the embodiment, it is assumed that an "IEC program" is an
example of the first program. The control device 100 executes the
IEC program at every predetermined control cycle T1 (first cycle)
to output a control command.
In this specification, the IEC program is a concept that covers a
program that can be scanned as a whole in each execution and output
a control command in each execution. The IEC program includes a
program composed of one or more instructions that are described
according to the international standard IEC61131-3 defined by the
International Electrotechnical Commission (IEC). The IEC program
may include a sequence instruction and/or a motion instruction.
Nevertheless, the IEC program is not limited to the instructions
defined in accordance with the international standard IEC61131-3,
and may include an instruction that is defined independently by the
manufacturer or vendor of the PLC (programmable logic controller).
Thus, the IEC program is suitable for control that requires
immediacy and high speed.
Since the IEC program may be created by the user according to the
control object or application, in the following descriptions, the
IEC program is also referred to as a "user program" for
convenience.
In this specification, the "sequence instruction" is a term that
covers one or more instructions described by one or more logic
circuits for calculating input values, output values, internal
values, etc. In one control cycle T1, the "sequence instruction" is
executed from the beginning to the end, and in the next control
cycle T1, the "sequence instruction" is executed from the beginning
to the end again.
In this specification, the "motion instruction" is a term that
covers one or more instructions for calculating numerical values,
such as position, speed, acceleration, jerk, angle, angular speed,
angular acceleration, angular jerk, etc., as control commands for
an actuator, such as a servo motor. The "motion instruction" is
also executed from the beginning to the end of the program (motion
program) of the motion instruction, as described by a function
block or a numerical expression, in one control cycle T1.
The control command that is outputted by executing the user program
at every control cycle T1 typically includes on/off of the digital
output determined according to the sequence instruction, and an
analog output calculated according to the motion instruction.
In the embodiment, it is assumed that an "application program" is
an example of the second program.
In this specification, the "application program" includes any
program that is executed sequentially. Typically, the "application
program" includes a program that is described in any language
executable in an interpreter system, which sequentially executes
the program line by line. In the following descriptions, a program
that describes the behavior in CNC (computer numerical control) (or
referred to as a "NC program" hereinafter) is given as an example
of the "application program". Moreover, a program for controlling a
robot is given as another example of the "application program".
The NC program is described according to a predetermined language.
As an example, the NC program is described using "G language", and
the program for controlling a robot is usually described using a
dedicated robot language.
In the following descriptions, for example, including the device or
machine, including the control thereof, that performs a particular
process or operation using CNC (computer numerical control) and/or
a robot may be referred to as a "control application".
The control device 100 parses at least a part of the application
program at every application execution cycle T2 (second cycle),
which is longer than the control cycle T1 (first cycle), to
sequentially generate an internal command, and outputs a control
command at every control cycle T1 according to the generated
internal command. Thus, the control device 100 parses the
application program to sequentially generate the internal command,
and outputs the control command at every control cycle T1 based on
the internal command.
Since the sequentially executed application program is inherently
unsuitable for processing for outputting the control command at a
fixed cycle, the internal command suitable for output of the
control command at every control cycle T1 is generated. Such an
internal command may be any code if it can output the control
command at every control cycle T1. Typically, the internal command
may be one or more functions with time as an input variable, or one
or more instructions with time as an argument.
In the control device 100, a process of outputting the control
command according to the sequence instruction included in the user
program, a process of outputting the control command according to
the motion instruction included in the user program, a process of
parsing the application program to generate the internal command,
and a process of outputting the control command according to the
internal command are executed. In addition to these processes,
other related processes are also executed in the control device
100. That is, in the control device 100, a plurality of processes
are executed using common processing resources.
Execution of such processes is managed by a function called a
scheduler. The scheduler allocates the processing time (or referred
to as "processor resource" hereinafter) of one or more processors
possessed by the control device 100 to the target processes.
In the embodiment, allocation of the processor resource is managed
in units of "tasks" composed of one or more processes. Priority is
preset for each task, and the scheduler allocates the processor
resource to one or more tasks based on the preset priorities.
An execution cycle may be set for each task. When the execution
cycle is set, the scheduler triggers the process set in the task in
accordance with the preset execution cycle.
FIG. 1A shows an example of five tasks (first to fifth tasks) set
for each priority.
The first task 10 includes an input/output refresh process (marked
as "O/I" in FIG. 1A and FIG. 1B) for updating the input value and
the control command with a field.
The second task 18 includes a sequence instruction execution
process 12, an output process 14 for outputting a control command
according to the application program, and an output process 16 for
outputting a control command according to the motion instruction
included in the user program. In the scheduler, execution of the
application program and processing execution of the control command
output are set as the second task 18 that has a relatively high
priority.
The first task 10 and the second task 18 are triggered at every
control cycle T1. Therefore, relatively high priorities are set to
the first task 10 and the second task 18. In the following
descriptions, the first task 10 and the second task 18 are also
referred to as "high priority tasks".
The third task 20 includes a process of parsing the application
program to sequentially generate an internal command. That is, in
the scheduler, processing execution of parsing of the application
program is set as the third task 20 that has a relatively low
priority.
The fourth task 22 includes any process provided by the control
device 100. That is, in the scheduler, execution of processing
contents different from the second task 18 and the third task 20 is
set as the fourth task 22 that has a relatively low priority.
The fifth task 24 includes a process such as data communication
between the control device 100 and an external device (or referred
to as "system service" hereinafter).
The third task 20, the fourth task 22, and the fifth task 24 are
executed during a period when the high priority task is not
executed. In the following descriptions, the third task 20, the
fourth task 22, and the fifth task 24 are also referred to as "low
priority tasks".
Priorities are respectively set for the first to fifth tasks, and
the processor resource is allocated according to the set
priorities.
FIG. 1A shows an example where a higher priority than the third
task 20 is set for the fourth task 22. In the example shown in FIG.
1A, the first task 10 and the second task 18 are repeatedly
executed at every control cycle T1. In each control cycle T1,
during the period when the first task 10 and the second task 18 are
not executed, the third to fifth tasks are executed according to
the priority.
In the example shown in FIG. 1A, the processor resource is
allocated to the fourth task 22 at every control cycle T1. On the
other hand, the processor resource is allocated to the third task
20 only during the period when none of the first task 10, the
second task 18, and the fourth task 22 is executed. Therefore, a
time equivalent to three control cycles T1 is required for
completing one process of the third task 20. That is, a time that
is three times the control cycle T1 is required from the triggering
of the third task 20 to the completion of the designated
process.
As described above, the process set as the third task 20 is to
parse the application program and sequentially generate the
internal command, and the sequentially generated internal command
is used for outputting the control command.
Thus, in the third task 20, the application program is parsed to
generate the internal command, and in the second task 18, the
internal command generated in the third task 20 is used
sequentially for calculation of the control command (that is,
"consumed" at every control cycle T1). That is, there is
competition between generation of the internal command performed by
the third task 20 and use of the internal command performed by the
second task 18.
In the case where sufficient processor resource is allocated to the
third task 20, a certain amount of the internal command can be
generated in advance before use of the internal command performed
by the second task 18. On the other hand, in the case where
sufficient processor resource cannot be allocated to the third task
20, use of the internal command performed by the second task 18
comes first, and it may be required to wait for generation of the
internal command performed by the third task 20.
Therefore, in the control device 100 according to the embodiment,
the processing state of the third task 20 (the parsing process for
the application program) is monitored, and when the processing
state meets a predetermined condition, the priority that has been
set to the third task 20 is changed according to the condition.
For example, in the case where there is no margin for generation of
the internal command, the priority set to the third task 20 is
raised. On the contrary, when there is a sufficient margin for
generation of the internal command, it is possible to lower the
priority set to the third task 20.
FIG. 1B shows an example of processing when the priority of the
third task 20 is set higher than the priority in the case of FIG.
1A. In FIG. 1B, the priority of the third task 20 is set higher
than the priority of the fourth task 22.
In the example shown in FIG. 1B, during the period when none of the
first task 10 and the second task 18 are executed, the processor
resource is preferentially allocated to the third task 20. As a
result, more processor resource is allocated to the third task 20
than in the case of FIG. 1A, and the designated process can be
completed in a time, which is twice the control cycle T1, after the
third task 20 is triggered. That is, the internal command can be
generated from the code to be processed by the application program
in a shorter time.
As compared with the case of FIG. 1A, more processor resource can
be allocated in FIG. 1B, and in this case, a larger amount of the
internal command can be generated by executing one process.
As described above, by dynamically changing the priority of the
third task 20, which includes the process of parsing the
application program and generating the internal command, according
to the processing state, output of the control command at every
control cycle T1 can be continued without interruption.
According to the control device 100 of the embodiment, for example,
in the case where the CNC machine tool or robot is controlled
according to the application program, the control command, such as
position and speed, can be outputted in synchronization with the
update cycle of the control command according to the user program.
Therefore, it is possible to realize control of synchronizing the
CNC machine tool and/or the robot and the related conveying device.
In this case, by adopting the aforementioned configuration, the
internal command for outputting the control command for the CNC
machine tool and/or the robot can be generated without a break, and
accurate and high-speed control and production can be realized
without causing the CNC machine tool and/or the robot to stop
temporarily during the processing.
In order to simplify the illustration, FIG. 1A and FIG. 1B show a
configuration that one single processor resource is time-divided
and allocated to multiple tasks. However, application of the
invention is not limited to such an environment and the invention
can be applied to other known program execution environments. For
example, in a multi-core or multi-processor environment, a
plurality of processor resources can be time-divided and allocated
to the necessary tasks respectively. In such a case, allocation of
the processor resources is still performed based on priority. Thus,
by applying the priority change process as described above, it is
possible to achieve the same effect as that described above.
Hereinafter, a more detailed configuration and processing of the
control device 100 according to the embodiment are described as a
more specific example of application of the invention.
B. Example of Overall Configuration of Control System
First, an example of the overall configuration of a control system
1 that includes the control device 100 according to the embodiment
is described. FIG. 2 is a schematic diagram showing an example of
the overall configuration of the control system 1 according to the
embodiment. FIG. 2 shows the control system 1 centered on the
control device 100 according to the embodiment.
Referring to FIG. 2, the control device 100 corresponds to an
industrial controller that controls control objects, such as
various equipment and devices. The control device 100 is a type of
computer that executes a control operation which will be described
later, and typically the control device 100 may be embodied as a
PLC (programmable logic controller). The control device 100 may be
connected to various field instruments 500 via a field network 2.
The control device 100 exchanges data with one or more field
instruments 500 via the field network 2 or the like. Generally, the
"field network" is also referred to as a "field bus", but for
simplicity, it is collectively referred to as "field network" in
the following descriptions. That is to say, the "field network" in
this specification is a concept that may cover the "field bus" in
addition to the "field network" in a narrow sense.
A bus or network that performs periodic communication, by which
data arrival time is guaranteed, may serve as the field network 2.
The bus or network that performs periodic communication may be
EtherCAT (registered trademark), EtherNet/IP (registered
trademark), DeviceNet (registered trademark), CompoNet (registered
trademark), etc.
Any field instruments 500 can be connected to the field network 2.
The field instruments 500 include an actuator that applies some
physical action to a manufacturing device or production line (or
collectively referred to as a "field" hereinafter), and an
input/output device that exchanges information with the field.
Data is exchanged between the control device 100 and the field
instruments 500 via the field network 2, but the exchanged data is
updated at a very short cycle of several hundreds of .mu.sec order
to several tens of msec order. Such data exchange includes a
process of transmitting data collected or generated in the field
instrument 500 (or referred to as "input data" hereinafter) to the
control device 100, and a process of transmitting data such as the
control command for the field instrument 500 (or referred to as
"output data" hereinafter) from the control device 100. The process
of updating such exchanged data corresponds to the aforementioned
"input/output refresh process".
In the configuration example shown in FIG. 2, the field instruments
500 include a remote I/O (input/output) device 510, a robot 520 and
a robot controller 522, a CNC machine tool 530, a servo driver 540,
and a servo motor 542.
The servo motor 542 drives a conveyor 544 to convey a workpiece W
to a worktable 546 disposed in front of the CNC machine tool 530.
The robot 520 places the unprocessed workpiece W on the worktable
546 into the CNC machine tool 530, and retrieves the processed
workpiece W in the CNC machine tool 530 and places it on the
worktable 546.
However, the field instruments 500 are not limited to the
aforementioned, and any device (for example, a visual sensor, etc.)
for collecting the input data and any device (for example, an
inverter device, etc.) for applying some action according to the
output data can serve as the field instruments 500.
Typically, the remote I/O device 510 includes a communication
coupler for communication via the field network 2, and an
input/output part (or referred to as an "I/O unit" hereinafter) for
acquiring the input data and outputting the output data.
A device that collects input data of an input relay or various
sensors (for example, analog sensor, temperature sensor, vibration
sensor, etc.) and a device that applies some action to the fields,
such as an output relay, a contactor, a servo driver, and any other
actuator, are connected to the remote I/O device 510.
The robot controller 522 performs trajectory calculation and angle
calculation of each axis according to the control command (position
command or speed command) from the control device 100, and drives
the servo motor, etc. that constitutes the robot 520 according to
the calculation result.
The CNC machine tool 530 machines any object by controlling a
machining center, etc. according to the program that specifies the
position, speed, etc. Typically, the CNC machine tool 530 includes
machining devices for lathe machining, milling machine, electric
discharge machining, etc.
The servo driver 540 drives the servo motor 542 according to the
control command (for example, position command or speed command)
from the control device 100.
The control device 100 may be connected to another device via a
host network 6. The host network 6 may be EtherNet (registered
trademark) or EtherNet/IP (registered trademark) which is a general
network protocol. More specifically, one or more server devices 300
and one or more display devices 400 may be connected to the host
network 6.
It is assumed that a database system, a manufacturing execution
system (MES), etc. serve as the server devices 300. The
manufacturing execution system acquires information from
manufacturing devices or equipment of the control object to monitor
and manage the entire production, and can handle order information,
quality information, shipping information, etc. Nevertheless, the
invention is not limited thereto, and a device that provides an
information-based service may be connected to the host network 6.
It is assumed that the information-based service is a process for
acquiring information from the manufacturing devices or equipment
of the control object to perform macro or micro analysis. For
example, data mining for extracting some characteristic trend
included in the information from the manufacturing devices or
equipment of the control object, or a machine learning tool for
performing machine learning based on the information from the
equipment or machine of the control object is assumed.
The display device 400 receives an operation from the user and
outputs a command, etc. corresponding to the user operation to the
control device 100, and graphically displays a calculation result,
etc. in the control device 100.
Furthermore, a support device 200 can be connected to the control
device 100. The support device 200 is a device that supports
preparation required for the control device 100 to control the
control object 100. Specifically, the support device 200 provides a
development environment of the program to be executed by the
control device 100 (program creation editing tool, parser,
compiler, etc.), a setting environment for setting parameters
(configurations) of the control device 100 and various devices
connected to the control device 100, a function of outputting the
created user program to the control device 100, a function of
modifying/changing online the user program to be executed on the
control device 100, etc.
C. Example of Hardware Configuration of Control Device
Next, an example of the hardware configuration of the control
device 100 according to the embodiment will be described. FIG. 3 is
a block diagram showing an example of the hardware configuration of
the control device 100 according to the embodiment.
Referring to FIG. 3, the control device 100 is an arithmetic
processing part called a CPU unit, and includes a processor 102, a
chipset 104, a main memory 106, a storage 108, a host network
controller 110, a USB (universal serial bus) controller 112, a
memory card interface 114, an internal bus controller 120, and a
field network controller 130.
The processor 102 comprises a CPU (central processing unit), an MPU
(micro processing unit), a GPU (graphics processing unit), etc. A
configuration having a plurality of cores may be adopted to serve
as the processor 102, and a plurality of processors 102 may be
disposed. That is, the control device 100 has one or more
processors 102 and/or the processor 102 having one or more cores.
The chipset 104 realizes the processing of the entire control
device 100 by controlling the processor 102 and the peripheral
elements. The main memory 106 comprises a volatile storage device,
such as DRAM (dynamic random access memory) or SRAM (static random
access memory). The storage 108 comprises for example a
non-volatile storage device, such as HDD (hard disk drive) or SSD
(solid state drive).
The processor 102 reads various programs stored in the storage 108
and develops them in the main memory 106 to execute them, thereby
realizing control corresponding to the control object and various
processes which will be described later. In addition to a system
program 34 for realizing the basic function, a user program 30 and
an application program 32 created corresponding to the
manufacturing device or equipment of the control object are stored
in the storage 108.
The host network controller 110 controls exchange of data with the
server device 300, the display device 400 (see FIG. 3), etc. via
the host network 6. The USB controller 112 controls exchange of
data with the support device 200 via USB connection.
The memory card interface 114 is configured to allow the memory
card 116 to be attached thereto or detached therefrom, and is
capable of writing data to the memory card 116 and reading various
data (user program, trace data, etc.) from the memory card 116.
The internal bus controller 120 controls the exchange of data with
I/O units 122 that are attached to the control device 100. The
field network controller 130 controls the exchange of data with
field devices via the field network 2.
FIG. 3 shows a configuration example that the required functions
are provided by execution of the programs performed by the
processor 102. However, a part or all of the provided functions may
also be implemented by using a dedicated hardware circuit (for
example, ASIC or FPGA). Alternatively, the main parts of the
control device 100 may be realized by using hardware according to a
general-purpose architecture (for example, an industrial personal
computer based on a general-purpose personal computer). In this
case, a plurality of OSs (operating systems) for different uses may
be executed in parallel by using a virtualization technique, and
the required applications may be executed on the respective
OSs.
In the control system 1 shown in FIG. 2, the control device 100,
the support device 200, and the display device 400 are configured
separately. However, it is also possible to adopt a configuration
that all or a part of these functions are integrated in one single
device.
D. Example of Functional Configuration of Control Device
Next, an example of the functional configuration of the control
device 100 according to the embodiment will be described. FIG. 4 is
a block diagram showing an example of the functional configuration
of the control device 100 according to the embodiment.
FIG. 4 shows a configuration example that the control device 100
controls a control application 1 and a control application 2.
Typically, each of the control application 1 and the control
application 2 includes I/O devices, such as a relay and a
contactor, and various actuators, such as a servo motor. In
addition to the control application 1 and the control application
2, other I/O devices and various sensors are also connected to the
control device 100 via the field network 2.
The control device 100 receives instructions of start/end of
production from the server device 300, etc. connected via the host
network 6. The server device 300 may also transmit recipe
information 38 (information of the product type or parameters
suitable for production) to the control device 100. The control
device 100 may also be connected to another control device 100 (not
shown) via a network.
Referring to FIG. 4, the control device 100 includes a PLC
processing engine 150, an application parsing part 160, an
application arbitration part 162, a control command calculation
part 164, a shared memory 170, a shared memory control part 172, a
display function part 174, a field network interface 176, and a
host network interface 178.
The PLC processing engine 150 manages the execution of the user
program 30 and the processing of the entire control device 100.
More specifically, the PLC processing engine 150 includes a
sequence program execution part 152, a scheduler 154, and a
priority changing part 156.
The sequence program execution part 152 executes (scans) the user
program 30 at every control cycle T1 to output a control
command.
The scheduler 154 mediates the order of the processes to be
executed in the control device 100, and more specifically,
allocates the processor resource to one or more tasks based on the
preset priorities.
The priority changing part 156 monitors the processing state of the
application parsing part 160, and when the processing state of the
application parsing part 160 meets a predetermined condition, the
priority changing part 156 changes the priority that has been set
to the task, which includes the processing of the application
parsing part 160, according to the condition. The priority changing
part 156 adjusts the allocation of the processor resource to the
priority changing part 156 so that the generation of the internal
command performed by the application parsing part 160 is executed
with a margin.
The priority changing part 156 has condition setting information
158 for changing the priority. The condition setting information
158 includes a condition and a content of a priority changing
process when the condition is met, as described later.
The application parsing part 160 parses at least a part of the
application program 32 and generates an internal command 40.
Different types of application programs 32 may be provided to the
application parsing part 160. The application parsing part 160 may
execute a pre-stored application program 32, or may execute an
application program 32 appropriately transmitted from the server
device 300.
The control command calculation part 164 calculates a control
command at every control cycle T1 according to the motion
instruction included in the user program 30. In addition, the
control command calculation part 164 calculates a control command
at every control cycle T1 according to the internal command 40
sequentially generated by the application parsing part 160.
The sequence program execution part 152 and the control command
calculation part 164 execute processing at every control cycle T1
(high priority task). On the other hand, the processing for the
application program 32 performed by the application parsing part
160 is executed at every application execution cycle T2 (second
cycle) which is an integral multiple of the control cycle T1 (low
priority task).
When multiple application programs 32 are processed in the
application parsing part 160, the application arbitration part 162
arbitrates the processing order thereof.
The shared memory 170 holds data to be shared among the PLC
processing engine 150, the application parsing part 160, and the
control command calculation part 164. The shared data may be stored
as a structure variable. For example, the internal command 40
generated sequentially by the application parsing part 160 is
sequentially written to the structure variable of the shared memory
170.
The shared memory control part 172 performs exclusive control of
writing and reading data to and from the shared memory 170 and
access to the shared memory 170 corresponding to an external
request. For example, the shared memory control part 172 gives the
data on the shared memory 170 to the field network interface 176,
so as to transmit it to any field instrument 500 connected via the
field network 2.
The display function part 174 outputs the data stored in the shared
memory 170 and the processing result from the application parsing
part 160 to a user, etc.
The field network interface 176 mediates the exchange of data with
the field instrument 500 that is connected via the field network
2.
The host network interface 178 mediates the exchange of data with
the device that is connected via the host network 6.
E. An Example of Internal Command
Next, an example of the internal command 40 generated by parsing
the application program 32 performed by the application parsing
part 160 of the control device 100 will be described. Any program
described in any language that is executable in an interpreter
system can be adopted as the application program 32. However, in
the following descriptions, a program defining a trajectory by one
or more commands in advance, like an NC program or a robot program
is assumed.
FIG. 5A and FIG. 5B are schematic diagrams for illustrating the
generation process of the internal command 40 in the control device
100 according to the embodiment. Referring to FIG. 5A, the
application parsing part 160 parses the application program 32, and
each instruction included in the application program 32 is parsed
((1) parse application program). By parsing the application program
32, the defined trajectory is generated internally ((2) generate
trajectory). Since the application program 32 usually includes an
instruction that defines a trajectory for each section, a
trajectory is generated for each section corresponding to each
instruction.
In the case of defining a group composed of a plurality of axes, a
trajectory may be generated for each axis, or a trajectory defining
the behavior of all the axes belonging to the group may be
generated.
The application parsing part 160 generates the internal command 40
(typically, one or more functions) that indicates the generated
trajectory ((3) generate internal command). In the case where the
trajectory is defined for each section, the internal command 40 is
generated corresponding to each section.
As described above, the application parsing part 160 parses the
application program 32 to calculate a passing point on the
trajectory, and generates the internal command based on the
calculated passing point.
A plurality of sections may be defined by a common internal command
40, or one single section may be further divided to generate
respective internal commands 40. In other words, the instructions
of the application program 32 or the sections of the trajectory
defined by the instructions, and the number of the internal
commands 40 generated do not necessarily match each other, and they
may be generated arbitrarily. Moreover, the output form of the
internal command 40 may be designed appropriately in consideration
of the required time width, etc. of the control cycle T1.
As shown in FIG. 5A, the internal command 40 may be a function that
defines the relationship between time and an instruction value, for
example. In the example shown in FIG. 5A, the internally generated
trajectory can be defined by a combination of straight lines. As an
example, Fx1(t), Fx2(t), and Fx3(t) can be outputted to indicate
the relationship between time and speed of the trajectory of each
straight section (section 1 to section 3) with respect to the X
axis. For other axes (for example, Y axis and Z axis) belonging to
the same group, functions may be outputted respectively in the same
manner.
As shown in FIG. 5B, the control command calculation part 164
calculates the control command according to the generated internal
command 40 at every control cycle T1, so that the control command
is outputted at every control cycle T1 ((4) calculate instruction
value). That is, by inputting the time of each control cycle to the
function corresponding to each section, the instruction value at
that time can be determined uniquely. In the case of setting any
group, the instruction value may be synchronized and outputted with
respect to each axis belonging to the group.
FIG. 5A and FIG. 5B show an example of the command that is
described in the G language used in CNC. However, the invention is
not limited thereto. If the program is executed by any interpreter
system, any language may be used. In addition, the format of the
generated internal command 40 may differ corresponding to the
language format to be processed.
F. Execution Timing of Task
Next, an execution timing of each task in the control device 100
according to the embodiment will be described. FIG. 6 is a time
chart showing an example of task execution timing in the control
device 100 according to the embodiment.
Referring to FIG. 6, a first task 10 (input/output refresh process)
and a second task 18 (including the sequence instruction execution
process 12, the output process 14 of the control command according
to the application program, and the output process 16 of the
control command according to the motion instruction included in the
user program) are set as high priority tasks. A third task 20 (the
process of parsing the application program 32 to sequentially
generate the internal command 40) is set as the low priority
task.
The high priority task is executed at every control cycle T1. In
the output process 14 of the control command according to the
application program, the internal command 40 generated by the
application parsing part 160 is read (dequeued) from the shared
memory 170, and the control command in the control cycle T1 is
calculated.
The low priority task is executed at every application execution
cycle T2. The application execution cycle T2 is set in the unit of
an integral multiple of the control cycle T1 (twice in the example
shown in FIG. 6). That is, the application parsing part 160 parses
at least a part of the application program 32 to sequentially
generate the internal command 40 at every application execution
cycle T2. The generated internal command 40 is sequentially queued
(enqueued) to a buffer in the shared memory 170.
The process for the low priority task only needs to be completed
within the application execution cycle T2. Since the processor
resource is not allocated to the low priority task during the
period when the high priority task is executed, the low priority
task stands by in a suspended state.
The execution timing of each task as shown in FIG. 6, that is, the
allocation of the processor resource, is executed by the scheduler
154. The scheduler 154 allocates the processor resource for each
task based on the priority set to each task.
G. Change of Priority
Next, a process of changing the priority set to the low priority
task will be described. As shown in FIG. 1A and FIG. 1B, a
plurality of tasks other than the high priority tasks are executed
in parallel, and for these tasks, the processor resource is
allocated according to the priorities.
Such low priority tasks share the processor resource with other low
priority tasks. On the other hand, since the application program 32
includes commands of an interpreter system, the time required for
parsing varies depending on the type and combination of the
commands. Therefore, in some cases, the requested parsing process
cannot be completed within the application execution cycle T2. The
state where the process cannot be completed within the application
execution cycle T2 is also referred to as a "task execution cycle
excess".
FIG. 7 is a time chart showing an example of a task execution cycle
excess of the low priority task in the control device 100 according
to the embodiment. Referring to FIG. 7, the processing of the third
task 20 started in the application execution cycle T2 that starts
from the time t1 cannot be completed by the time t3, i.e., the end
of the original cycle, and the processing is completed in the next
application execution cycle T2.
When such a task execution cycle excess occurs, measures, such as
lengthening the application execution cycle T2 and/or changing to a
higher priority, may be taken.
The control device 100 according to the embodiment monitors the
processing state of the third task 20 (the parsing process for the
application program 32), and when the processing state meets a
predetermined condition, changes the priority that has been set to
the third task 20 according to the condition. The change according
to this condition may include raising the priority or lowering the
priority.
Typically, the priority changing part 156 of the control device 100
may raise the priority set to the third task 20 when the
aforementioned task execution cycle excess occurs, and after
raising the priority, restore the priority when another
predetermined condition is met.
The "processing state of the task" for changing the priority is a
concept that covers a state which can affect the calculation
processing of the control command using the internal command set as
a high priority task. The "processing state of the task" may
include any information required for avoiding a situation that
output of the control command according to the application program
32 at every control cycle T1 cannot be guaranteed.
The priority changing part 156 of the control device 100 determines
the processing state of the application parsing part 160 based on
the information that indicates the load related to the generation
process of the internal command performed by the application
parsing part 160. The following information is provided as examples
of the information that indicates the load related to the
generation process of the internal command.
(1) Time required for processing execution of the low priority
task
(2) Whether or not the task execution cycle excess occurs
(3) The number of passing point buffers for generating the internal
command
(4) The number of internal command buffers
(5) Special command in the application program
A priority changing process based on each information will be
described hereinafter.
(g1. Time Required for Processing Execution of the Low Priority
Task)
The aforementioned processing state of the task may be based on the
time required for the processing execution of the target low
priority task. Thus, the information that indicates the load
related to the generation process of the internal command may
include the time required for parsing of the application program 32
performed by the application parsing part 160.
A last value, a maximum value, a minimum value, an average value,
an intermediate value, etc. of the time required from the start to
the end of processing of the low priority task can serve as the
time required for the processing execution of the low priority
task.
Whether or not a task execution cycle excess has occurred on the
target low priority task, the number of the task execution cycle
excesses that occurred, etc. may also be used.
FIG. 8 is a diagram showing an example of a variable list that
shows the time required for the processing execution in the control
device 100 according to the embodiment. Referring to FIG. 8, the
control device 100 holds information required for the processing
execution of a specific task as a system variable.
In the example shown in FIG. 8, a task execution count variable 601
(_CNC_ServiceExecCount), an execution time last value variable 602
(_CNC_ServiceLastExecTime), an execution time maximum value 603
(_CNC_ServiceMaxExecTime), and an execution time minimum value 604
(_CNC_ServiceMinExecTime) are shown as a system variable group
600.
The task execution count variable 601 indicates a total number of
times that the target task has been executed since the control
device 100 starts (or since any reset timing). The execution time
last value variable 602 indicates the time required for processing
in the last execution of the target task. The execution time
maximum value 603 indicates the maximum value of the time required
for executing the task after the control device 100 starts (or
after any reset timing). The execution time minimum value 604
indicates the minimum value of the time required for executing the
task after the control device 100 starts (or after any reset
timing).
The load state, etc. of the target task can be evaluated based on
the time required for the processing execution of the low priority
task, and the priority of the target task can be changed based on
the evaluation result.
For example, a case where the last value of the processing
execution of the target task reaches a predetermined ratio (for
example, 90%) of the preset application execution cycle T2 can be
used as a condition for using the time required for the processing
execution as shown in FIG. 8. When this condition is met, the
priority of the target task may be raised.
Conversely, a case where the last value of the processing execution
of the target task is equal to or less than a predetermined ratio
(for example, 30%) of the preset application execution cycle T2
over multiple times can be used. When this condition is met, the
priority of the target task may be lowered.
Further, the degree to which the priority of the target task is to
be raised may be determined based on the difference or ratio
between the length of the application execution cycle T2 and the
time required for the processing execution of the target task.
Thus, the load state of the target task can be evaluated directly
by monitoring the time required for the processing execution of the
low priority task.
(g2. Whether or not the Task Execution Cycle Excess Occurs)
The aforementioned processing state of the task may also be based
on whether the task execution cycle excess occurs on the target low
priority task. That is, the information that indicates the load
related to the generation process of the internal command may
include information of whether or not the time required for parsing
of the application program 32 performed by the application parsing
part 160 exceeds the length of the application execution cycle T2
(second cycle).
Referring to FIG. 8 again, in the system variable group 600, a task
execution cycle excess variable 605 (_CNC_ServiceExceeded) and a
task execution cycle excess count variable 606
(_CNC_ServiceExceedCount) are further shown. The task execution
cycle excess variable 605 indicates whether or not a task execution
cycle excess has occurred in the last execution of the target task.
The task execution cycle excess count variable 606 indicates the
total number of times that the task execution cycle excess has
occurred since the control device 100 starts (or since any reset
timing).
The load state, etc. of the target task can be evaluated based on
whether the task execution cycle excess occurs, and the priority of
the target task can be changed based on the evaluation result. In
the case of using the information of whether the task execution
cycle excess occurs, the priority of the target task may be raised
on the condition that the task execution cycle excess occurs in the
last execution of the target task.
Conversely, the priority of the target task may be lowered on the
condition that the task execution cycle excess does not occur over
a predetermined number of times of execution.
Thus, the load state of the target task can be evaluated directly
by monitoring occurrence of the task execution cycle excess.
(g3. The Number of Passing Point Buffers for Generating the
Internal Command)
The aforementioned processing state of the task may be based on the
number of passing point buffers on a target trajectory that is
calculated by parsing the application program 32. That is, the
information that indicates the load related to the generation
process of the internal command may include the number of passing
points that the application parsing part 160 calculates in advance
for generating the internal command.
Here, a process of parsing the application program 32 to generate
the internal command 40 will be described. FIG. 9A and FIG. 9B are
schematic diagrams for illustrating an example of the generation
process of the internal command 40 in the control device 100
according to the embodiment. FIG. 9A shows a processing procedure
of generating the internal command 40 in the period from the time
t0 to the time t1, and FIG. 9B shows a processing procedure of
generating the internal command 40 in the period from the time t1
to the time t2.
Referring to FIG. 9A, the application parsing part 160 parses the
application program 32 to sequentially determine the target
trajectory. The application parsing part 160 sequentially
calculates passing points at predetermined intervals with respect
to the sequentially determined target trajectory. Each passing
point is calculated based on a moving distance on the target
trajectory and a moving speed on the target trajectory.
In the example shown in FIG. 9A, in addition to the passing point
P0 (t0) which is the initial position at the time t0, the passing
point P1 (t1) at the time t1, the passing point P2 (t2) at the time
t2, and the passing point P3 (t3) at the time t3 are
calculated.
The application parsing part 160 calculates a moving path 44 from
the passing point P0 (t0) to the passing point P1 (t1) at least
based on the information of the passing point P0 (t0) and the
passing point P1 (W. The application parsing part 160 generates an
internal command Fx1(t) from the calculated moving path 44. In FIG.
9A, only the internal command Fx1(t) is shown, but the internal
command 40 is actually generated corresponding to the number of the
motors that need to be controlled at the same time.
In addition to the information of the passing point P0 (t0) and the
passing point P1 (t1), the information of one or more passing
points following the passing point P1 (t1) may be reflected in the
calculation of the moving path 44. By referring to the information
of more passing points, the accuracy of generation of the internal
command can be improved.
Referring to FIG. 9B, for the period from the time t1 to the time
t2, the application parsing part 160 further parses the application
program 32 to further determine a further target trajectory. The
application parsing part 160 calculates a new passing point P4 (t4)
for the further target trajectory that has been further
determined.
Then, the application parsing part 160 calculates the moving path
44 from the passing point P1 (t1) to the passing point P2 (t2),
based on the information of the passing point P1 (t1) and the
passing point P2 (t2). The application parsing part 160 generates
an internal command Fx2(t) from the calculated moving path 44. In
FIG. 9B, only the internal command Fx2(t) is shown, but the
internal command 40 is actually generated corresponding to the
number of the motors that need to be controlled at the same
time.
By repeating the processing procedure as described above, the
internal command 40 for realizing the target trajectory is
sequentially generated.
FIG. 10 is a schematic diagram showing an example of processing of
a passing point for generating the internal command 40 in the
control device 100 according to the embodiment. Referring to FIG.
10, a passing point buffer 50 is prepared in the application
parsing part 160. Information (typically, coordinate values) of the
sequentially calculated passing points is queued (enqueued)
according to a calculation order thereof in the passing point
buffer 50. From the passing point buffer 50, the information of the
passing points is read (dequeued) according to the calculation
order, and the corresponding internal command 40 is sequentially
generated.
The number of pieces of the information of the passing points
stored in the passing point buffer 50 shown in FIG. 10 is also
referred to as a "passing point buffer number". The passing point
buffer number indicates the likelihood for sequentially generating
the internal command 40. That is, as the passing point buffer
number increases, even if there is a variation in processing time
in the parsing process of the application program 32 performed by
the application parsing part 160, the generation process of the
internal command 40 can be continued without being suspended.
The load state, etc. of the target task can be evaluated based on
the number of passing points stored in the passing point buffer 50
of the application parsing part 160, and the priority of the target
task can be changed based on the evaluation result.
In the case of using the number of pieces of information of the
passing points (the passing point buffer number) stored in the
passing point buffer 50 as shown in FIG. 10, for example, a
condition of whether or not the passing point buffer number is
lower than a predetermined threshold value can be adopted. When
this condition is met, the priority of the target task may be
raised.
Conversely, if the passing point buffer number remains higher than
the predetermined threshold value over a predetermined period, the
priority of the target task may be lowered.
Thus, the load state of the target task can be evaluated by
monitoring the number of passing points stored in the passing point
buffer 50 of the application parsing part 160.
(g4. The Number of Internal Command Buffers)
The aforementioned processing state of the task may be based on the
number of buffers of the internal command 40 generated from the
application program 32. That is, the information that indicates the
load related to the generation process of the internal command may
include the number of internal commands that have not yet been
processed by the control command calculation part 164 among the
internal commands generated by the application parsing part
160.
The control command calculation part 164 of the control device 100
calculates the control command at every control cycle T1 according
to the internal command 40 sequentially generated by the
application parsing part 160.
FIG. 11 is a schematic diagram showing an example of processing for
calculating the control command from the internal command 40 in the
control device 100 according to the embodiment. Referring to FIG.
11, in the shared memory 170, an internal command buffer 60 is
prepared for storing the internal command sequentially generated by
the application parsing part 160. In the internal command buffer
60, the sequentially calculated internal commands are queued
(enqueued) according to a generation order thereof. From the
internal command buffer 60, the internal commands are read
(dequeued) according to the generation order, and used by the
control command calculation part 164 for calculation of the control
command.
The number of internal commands 40 stored in the internal command
buffer 60 shown in FIG. 11 is also referred to as an "internal
command buffer number". The internal command buffer number
indicates the likelihood for the control command calculation part
164 to calculate the control command at every control cycle T1.
That is, as the internal command buffer number increases, even if
there is a variation in processing time in the generation process
of the internal command 40 performed by the application parsing
part 160, the output of the control command can be continued
without suspending the calculation process of the control command
at every control cycle T1.
The load state, etc. of the target task can be evaluated based on
the number of internal commands 40 stored in the internal command
buffer 60, and the priority of the target task can be changed based
on the evaluation result.
In the case of using the number of internal commands (the internal
command buffer number) stored in the internal command buffer 60 as
shown in FIG. 11, for example, a condition of whether or not the
internal command buffer number is lower than a predetermined
threshold value can be adopted. When this condition is met, the
priority of the target task may be raised.
Conversely, if the internal command buffer number remains higher
than the predetermined threshold value over a predetermined period,
the priority of the target task may be lowered.
Thus, the load state of the target task can be evaluated by
monitoring the number of internal commands stored in the internal
command buffer 60 of the shared memory 170.
(g5. Special Command in the Application Program)
When a special command described in the application program 32 is
executed as the aforementioned processing state of the task, the
priority of the target task or the related task may be changed
based on the special command. That is, the information that
indicates the load related to the generation process of the
internal command may include the special command explicitly
described in the application program 32.
FIG. 12A and FIG. 12B are schematic diagrams showing an example of
the application program processed in the control device 100
according to the embodiment. FIG. 12A shows an example of an
application program 32A described in the G language, and FIG. 12B
shows an example of an application program 32B described in the
robot language.
Referring to FIG. 12A, the application program 32A includes a
special command 320 in a "050" block. The special command 320 is an
instruction for doubling the generation accuracy of the internal
command 40. When the application parsing part 160 executes the
special command 320, a message is sent to the priority changing
part 156. The priority changing part 156 changes the priority with
respect to the task processing the application program 32A, based
on the content of the message from the application parsing part
160.
Similarly, referring to FIG. 12B, the application program 32B
includes a special command 322 in the middle of a series of
commands. The special command 322 is an instruction for operating
the application program 32B and another application program in
conjunction with each other. That is, the processing for another
application program is started by executing the special command
322.
When the application parsing part 160 executes the special command
322, a message is sent to the priority changing part 156. The
priority changing part 156 changes the priority with respect to the
task processing the application program that is newly started from
the application program 32B, based on the content of the message
from the application parsing part 160. Alternatively, the priority
with respect to the task that processes the application program 32B
may be changed.
Nevertheless, the application programs 32A and 32B shown in FIG.
12A and FIG. 12B are merely examples, and any special command may
be defined.
Thus, by explicitly defining the special command in the application
program to be processed by the application parsing part 160, it is
possible to change the priority of the task that processes the
application program in advance, and realize accurate priority
adjustment with estimation of the future load of the target
task.
(g6. Others)
The above descriptions illustrate multiple factors that can be the
information indicating the load related to the generation process
of the internal command. However, it is also possible to use only
one of these factors or use any of these factors in combination.
Furthermore, when multiple factors are combined, weighting
corresponding to the factors may be applied. As a form of
utilization of these factors, a method corresponding to the state
can be applied.
H. Processing Procedure Related to Change of Priority
Next, a processing procedure related to change of the priority set
to the low priority task will be described. FIG. 13 is a flowchart
showing the processing procedure of priority change in the control
device 100 according to the embodiment. Typically, each step shown
in FIG. 13 is realized by execution of the system program 34
performed by the processor 102 of the control device 100.
Referring to FIG. 13, the priority changing part 156 of the PLC
processing engine 150 collects information related to the condition
defined in the condition setting information 158 (Step S100). Then,
the priority changing part 156 determines whether the collected
information meets any of the conditions defined in the condition
setting information 158 (Step S102).
If the collected information does not meet any of the conditions
defined in the condition setting information 158 (NO in Step S102),
the processing starting from Step S100 is repeated.
On the other hand, if the collected information meets any of the
conditions defined in the condition setting information 158 (YES in
Step S102), the priority changing part 156 changes the priority
with respect to the target task according to the content
corresponding to the met condition (Step S104). Then, the
processing starting from Step S100 is repeated.
For example, a series of processes as shown in FIG. 13 may be
repeatedly executed at every control cycle T1.
I. Priority Arbitration Among Multiple Application Programs
For convenience, the above descriptions illustrate a case where one
application program 32 is executed in the control device 100 as an
example. However, a plurality of application programs 32 can be
executed in parallel. In that case, in addition to changing the
priority with respect to the task that processes each application
program, the priorities of the tasks that process the respective
application programs may also be changed relatively (that is,
arbitration of the priority).
FIG. 14 is a time chart showing an example of execution timing when
a plurality of application programs are executed in parallel in the
control device 100 according to the embodiment. The time chart
shown in FIG. 14 shows an example that an application program 1
parsed at every application execution cycle T21 and an application
program 2 parsed at every application execution cycle T22 are
executed in parallel.
Referring to FIG. 14, in addition to the first task 10
(input/output refresh process), the sequence instruction execution
process 12, the output process 16 of the control command according
to the motion instruction included in the user program, an output
process 14-1 of a control command according to the application
program 1, and an output process 14-2 of a control command
according to the application program 2 are set as high priority
tasks.
The parsing of the application program 1 and the parsing of the
application program 2 are set as low priority tasks.
In the example shown in FIG. 14, independent processor resources
can be allocated to the high priority tasks and the low priority
tasks respectively.
More specifically, the application parsing part 160 parses at least
a part of the application program 1 at every application execution
cycle T21 (twice the control cycle in the example shown in FIG. 14)
to sequentially generate the internal command 40. The generated
internal command 40 is sequentially queued (enqueued) to the buffer
in a shared memory 170-1.
In addition, the application parsing part 160 parses at least a
part of the application program 2 at every application execution
cycle T22 (twice the control cycle in the example shown in FIG. 14)
to sequentially generate the internal command 40. The generated
internal command 40 is sequentially queued (enqueued) to the buffer
in a shared memory 170-2.
Two application parsing parts 160 that are independent of each
other may be prepared for processing the application program 1 and
the application program 2 respectively.
In such a configuration, a common processor resource is shared by
the low priority tasks. That is, the processor resource for the low
priority tasks is allocated based on the relative relationship
between the priorities respectively set to the low priority tasks.
Therefore, the priority changing process as described above may be
applied to each task that is set as a low priority task or be
applied for making an adjustment to the relative relationship
between the priorities of the tasks.
Regarding making an adjustment to the relative relationship between
the priorities of the tasks, for example, when the condition for
raising the priority of one task is met, the priority of the task
may be raised, but the priority of another task may be lowered.
That is, when the condition that one of the tasks should be
preferentially processed is met, the priority of the target task
may be set relatively higher than the priorities of other tasks,
and the implementation method thereof is not particularly
limited.
Thus, in the case where a plurality of tasks are set as the low
priority tasks, arbitration may be performed between the priorities
of the tasks. In other words, in the case where the application
parsing part 160 performs parsing respectively on multiple
application programs 32 to sequentially generate the respective
internal commands, the priority changing part 156 may change the
priorities of multiple tasks respectively associated with the
parsing of the application programs 32. Such arbitration of
priorities may be realized by conjunction of the application
arbitration part 162 and the priority changing part 156 (both are
shown in FIG. 4).
J. Overlap Operation
Next, an overlap operation among multiple control applications
using the control device 100 according to the embodiment will be
described.
FIG. 15 is a schematic diagram for illustrating the overlap
operation provided by the control device 100 according to the
embodiment. FIG. 15 shows an application example for a
configuration that includes the robot 520 and the CNC machine tool
530 as shown in FIG. 2, for example. As a specific operation, the
robot 520 picks up the workpiece W conveyed by the conveyor 544 and
places it inside the CNC machine tool 530. The CNC machine tool 530
performs a machining process on the workpiece W. Then, the robot
520 takes the workpiece W out of the CNC machine tool 530 and
places the workpiece W at a receiving position of the next
process.
In order to improve the productivity, for example, in such a series
of operations, the robot 520 may be moved to a take-out position of
the workpiece W before the machining performed on the workpiece W
in the CNC machine tool 530 is completed. That is, the CNC machine
tool 530 and the robot 520 need to be operated in parallel in a
state of a certain relationship. The operation of multiple control
applications in the state of a certain relationship is also
referred to as the "overlap operation" hereinafter.
More specifically, the "overlap operation" includes a state, in
which after the operation according to an application program
starts, the operation according to another application program
follows and starts. A condition for starting the operation
according to another application program (or referred to as an
"overlap condition" hereinafter) includes the lapse of a
predetermined time after the operation starts, arrival at a
predetermined position, etc.
FIG. 15 shows an example of the operation immediately before the
machining performed on the workpiece W in the CNC machine tool 530
is completed. If the machining process of the workpiece W in the
CNC machine tool 530 is completed at a time t2, the robot 520 may
take out the workpiece W which has been machined at the time t2.
Therefore, the robot 520 starts to operate from a time t1 so that
the robot 520 can arrive at a workpiece take-out position of the
CNC machine tool 530 at the time t2. Then, the robot 520 takes out
the workpiece W at the time t2 and starts to move to the next
process from a time t3. Meanwhile, as soon as the workpiece W is
taken out by the robot 520, the CNC machine tool 530 starts to move
to the receiving position for receiving a new workpiece W.
Thus, the productivity can be improved by linking the CNC machine
tool 530 and the robot 520 to each other and operating the CNC
machine tool 530 and the robot 520 in parallel.
The configuration and processing for realizing the overlap
operation will be described hereinafter. The "overlap operation" in
this specification may cover a case where a plurality of control
applications start operating at the same time with any timing as a
reference.
FIG. 16 is a schematic diagram showing an example of the program
for realizing the overlap operation in the control device 100
according to the embodiment. The user program 30 shown in FIG. 16
is directed to the control of the conveyor 544, the CNC machine
tool 530, and the robot 520 shown in FIG. 2.
More specifically, the user program 30 includes a function block
302 that defines the motion instruction for controlling the servo
motor 542 that drives the conveyor 544, a function block 304 that
instructs start of execution of an application program 32-1 (NC
program) for controlling the CNC machine tool 530, and a function
block 306 that instructs start of execution of an application
program 32-2 (robot program) for controlling the robot 520.
Each of the function blocks 302, 304, and 306 executes a specified
process when an operation start flag becomes TRUE.
A special command for performing the overlap operation is added to
the application program 32-1 and the application program 32-2. FIG.
16 shows an example of overlapping "MOVE X200 Y100" defined in the
third line of the application program 32-2 with the operation
according to the command "G01 X-10 Y-50" defined in the 049 block
of the application program 32-1.
In order to realize the overlap operation, a special command 342 is
defined immediately after the command ("G01 X-10 Y-50" in the 049
block) that defines the preceding operation. In addition to the
instruction "OverlapMove", the special command 342 is added with
identification information ("1" as an argument in the example shown
in FIG. 16) for specifying the instruction.
On the other hand, a special command 344 is defined in the
application program 32-2 immediately before the command ("MOVE X200
Y100" in the example shown in FIG. 16) that defines the operation
to be overlapped. In addition to the instruction "OverlapStart",
the special command 344 is added with identification information
("1" in the example shown in FIG. 16) for specifying the
instruction and an overlap condition ("100 ms" in the example shown
in FIG. 16). Besides time and position, any information can be used
as the overlap condition.
FIG. 17 is a schematic diagram showing an example of the overlap
operation when time is set as the overlap condition. Referring to
FIG. 17, after the operation according to the command described in
the 049 block of the application program 32-1 starts, the operation
according to the command "MOVE X200 Y100" of the application
program 32-2 starts when "100 ms" which is the overlap condition
lapses. That is, the operation according to the application program
32-2 starts when the time defined in the overlap condition has
lapsed after the start of the operation specified by the
application program 32-1, so that they can overlap and operate with
each other.
FIG. 18 is a schematic diagram showing an example of the overlap
operation when position is set as the overlap condition. Referring
to FIG. 18, after the operation according to the command described
in the 049 block of the application program 32-1 starts, the
operation according to the command "MOVE X200 Y100" of the
application program 32-2 starts on the condition of arrival at a
predetermined position (or entry into a predetermined range), which
is the overlap condition. That is, the operation according to the
application program 32-2 starts when the condition of the position
defined in the overlap condition is met after the start of the
operation specified by the application program 32-1, so that they
can overlap and operate with each other.
FIG. 19 is a schematic diagram showing a functional configuration
for realizing the overlap operation in the control device 100
according to the embodiment. Referring to FIG. 19, the control
device 100 has two application parsing parts 160-1 and 160-2. The
application parsing parts 160-1 and 160-2 process the NC program
and the robot program respectively.
The internal commands generated by parsing of the application
program performed by the application parsing parts 160-1 and 160-2
are sequentially stored in the shared memory 170. The control
command calculation part 164 sequentially reads the internal
commands sequentially stored in the shared memory 170 and outputs a
control command 1 and a control command 2.
The control command calculation part 164 can determine the length
of the time required for processing the read internal command. For
example, each internal command is a function that defines the
relationship between time and the control command with respect to a
certain time range, and by referring to the time range that can be
inputted to the function, it is possible to calculate the time
required for reaching the specified target position.
The control command calculation part 164 can sequentially calculate
the time required for processing the internal command that is
currently executed, that is, a moving time required for moving from
the current position to the specified target position. The control
command calculation part 164 sequentially outputs the sequentially
calculated moving times to the application parsing parts 160-1 and
160-2.
The application parsing parts 160-1 and 160-2 can parse the
commands included in the application program to a certain extent
(that is, look ahead) to know in advance the existence of the
special command that is for instructing the overlap operation.
Moreover, information related to the overlap operation (typically,
the overlap condition) may be exchanged between the application
parsing part 160-1 and the application parsing part 160-2.
When the process proceeds right before the line where the special
command for instructing the overlap operation exists, the
application parsing parts 160-1 and 160-2 determine whether the
overlap condition can be met based on the moving time from the
control command calculation part 164. That is, the application
parsing parts 160-1 and 160-2 can know at what time point the
overlap operation needs to be started.
If it is determined in advance that the overlap operation cannot be
started based on the specified overlap condition, the application
parsing parts 160-1 and 160-2 send a request (priority change
request) to the priority changing part 156, so as to raise the
priority of the low priority task that includes the parsing process
of the application parsing parts 160-1 and 160-2. As a result, more
processor resource is allocated for the parsing of the application
program performed by the priority changing part 156, so that the
overlap operation can be started at the specified timing.
In other words, the parsing process of the required application
program can be completed before the time of start of the overlap
operation.
As described above, by dynamically changing the priority of the
task related to the parsing of the application program, the overlap
operation can be executed reliably.
Generally, the application program for controlling the CNC machine
tool and the application program for controlling the robot are
described in a language of the interpreter system which
sequentially executes the program line by line. For programs of
such an interpreter system, the moving distance, etc. specified by
each command varies depending on the type of the command and the
argument, etc., so the time required for processing each line
differs from command to command.
In addition, in the case of controlling the CNC machine tool and
the robot respectively with dedicated controllers, it would be
difficult to realize a dense overlap operation under the influence
of the control cycle of each controller, the communication cycle
between the controllers, etc.
In contrast thereto, in the control device 100 according to the
embodiment, multiple application programs can be parsed
respectively to output the control commands at every control cycle,
and the synchronous operation or the overlap operation between the
applications can be performed.
With such synchronous operation or the overlap operation, the
production device, in which the CNC machine tool and the robot are
linked, can be operated more efficiently, and the production
capacity can be increased.
K. Appendix
The embodiment described above includes the following technical
concepts.
[Configuration 1]
A control device (100) having one or more processors, the control
device comprising:
a storage part (108) storing a first program (30) that is scanned
as a whole for every execution and a second program (32) that is
executed sequentially;
a program execution part (152) executing the first program at every
first cycle to output a first control command;
a parsing part (160) parsing at least a part of the second program
at every second cycle, which is longer than the first cycle, to
sequentially generate an internal command;
a command calculation part (164) outputting a second control
command at every first cycle according to the internal command
generated by the parsing part;
a scheduler (154) allocating a processor resource to one or more
tasks based on a preset priority, wherein at least a first task
that has a first priority comprising processing execution performed
by the program execution part and the command calculation part, a
second task that has a second priority, lower than the first
priority, comprising processing execution performed by the parsing
part, and a third task that has a third priority comprising
execution of a processing content different from the first task and
the second task are set in the scheduler; and
a priority changing part (156) monitoring a processing state of the
parsing part, and when the processing state of the parsing part
meets a predetermined condition, changing the second priority that
has been set to the second task according to the condition.
[Configuration 2]
The control device according to configuration 1, wherein the
priority changing part determines the processing state of the
parsing part based on information that indicates a load related to
a generation process of the internal command performed by the
parsing part.
[Configuration 3]
The control device according to configuration 2, wherein the
information that indicates the load comprises a time (602; 603;
604) required for parsing of the second program performed by the
parsing part.
[Configuration 4]
The control device according to configuration 2 or 3, wherein the
information that indicates the load comprises information (605) of
whether the time required for parsing of the second program
performed by the parsing part exceeds a length of the second
cycle.
[Configuration 5]
The control device according to any of configurations 2 to 4,
wherein the parsing part is configured to parse the second program
to calculate a passing point on a trajectory and generate the
internal command based on the calculated passing point, wherein the
information that indicates the load comprises a number of passing
points that the parsing part calculates in advance for generating
the internal command.
[Configuration 6]
The control device according to any of configurations 2 to 5,
wherein the information that indicates the load comprises a number
of internal commands, which have not yet been processed by the
command calculation part, among the internal commands generated by
the parsing part.
[Configuration 7]
The control device according to any of configurations 2 to 6,
wherein the information that indicates the load comprises a special
command described in the second program.
[Configuration 8]
The control device according to any of configurations 1 to 7,
wherein the priority changing part raises the second priority that
has been set to the second task, and then restores the second
priority when another predetermined condition is met.
[Configuration 9]
The control device according to any of configurations 1 to 8,
wherein the parsing part is configured to execute parsing on a
plurality of the second programs respectively to sequentially
generate respective internal commands, wherein the priority
changing part changes priorities of a plurality of the second tasks
associated with the parsing of the second programs.
L. Advantages
By scheduling the processor resource, the control device according
to the embodiment can execute one or more application programs in
parallel in addition to the user program that includes the sequence
instruction and the motion instruction. Since the control command
can be outputted at every control cycle in such parallel execution,
it is possible to realize the same control accuracy in the control
according to the application program and the control according to
the user program.
The control device according to the embodiment parses the
application program that is composed of one or more commands
described in a language of the interpreter system to generate the
internal command, and calculates the control command based on the
generated internal command. The parsing process of the application
program and the calculation process of the control command need to
be executed in conjunction with each other. Therefore, the control
device according to the embodiment dynamically changes the priority
set to the task of the parsing according to the load state of the
process related to the parsing of the application program. Thus,
even when processing application programs with different required
times for parsing the commands, it is still possible to guarantee
the output of the control command at every control cycle.
The control device according to the embodiment can realize the
overlap operation, that is, after a lapse of start of the operation
according to one of a plurality of application programs, the
operation according to another application program is started. In
order to realize such an overlap operation, the control device
changes the priority of the task as required so that generation of
the required internal command can be completed in advance. By
realizing the overlap operation while utilizing dynamic change of
the priority of the task, the equipment can operate more
efficiently and thereby the production efficiency can be
improved.
The embodiments disclosed herein are exemplary in all aspects and
should not be construed restrictive. The scope of the invention is
defined by the claims instead of the above descriptions, and it is
intended to include the equivalent of the scope of the claims and
all modifications within the scope.
* * * * *